Sterols, phospholipids and ATPase activities will be studied in normal lenses and in cataracts produced by radiation, galactose, diazacholesterol and in normal lenses and senile cataracts in humans. Area/force measurements will be obtained with a surface tension balance on lipids from normal and cataractous lenses and on lipids from normal lenses to which selected lipids have been added to simulate the composition of cataract lipids.